Aircraft, and in particular helicopters, commonly employ searchlights for illumination during nighttime operation. Initially, such search lights were either hand held or fixed to the helicopter body. In time, helicopter searchlights were developed that allowed for crude control over the aiming of the light beam. This was generally accomplished by manually adjusting the position of the light via a handle or other apparatus extending into the helicopter.
Eventually, technology allowed for the creation of searchlights that could be controlled by electronic switches operated by the pilot from within the helicopter. These searchlights typically utilize analog circuitry containing electromechanical relays to switch electric current, and micro-switches to detect searchlight position. Such a system allows the searchlight to operate within a specific range of motion determined by the physical placement of the micro-switches.
There is currently a demand for a programmable helicopter searchlight having preset searchlight positions, wherein more flexible and readily adaptable operating envelopes are available. Existing searchlights using analog technology and micro-switches do not allow for this flexibility.
The present invention satisfies this need by providing a searchlight with multiple preset positions, that can be controlled with a discrete digital electronic circuit in conjunction with position sensing rotary potentiometers. In searchlights employing both a visible and an infrared beam, the circuit can also control which type of light is turned on. The potentiometers provide an input voltage to the electronic circuit that is proportionate to the position of the searchlight. The electronic circuit compares these voltages to preset values from a bank of adjustable trimpots located on the circuit board. A trimpot is assigned to each significant point in the searchlight's operating envelope. Based on the voltage comparison, the electronic logic circuit controls switching of the motors that move the searchlight. The operating envelope and the position of each preset can be altered merely by adjusting the corresponding trimpot on the circuit board.
In another embodiment of the invention, a microprocessor controlled electronic circuit is contemplated. In this embodiment, the operating envelope and position of the presets are adjustable by reprogramming the circuits rather than by adjusting the trimpots.